Conventionally, in a general relationship between a key and a lock(latch), mechanical irregularities formed at an insertion portion of a key body or magnetic force of an embedded magnet drive(s) a plurality of pins placed at an inner cylinder within the lock so as to move the pins extending over a boundary surface between the inner cylinder and a fixed outer cylinder. The inner cylinder is rotatable within the outer cylinder so as to be unlatched.
However, in such a mechanical combination of a key and a lock, unlocking is possible if the configuration of a duplicated key is the same as that of an original key, and further, it is difficult to protect such a mechanical lock from subversive activities.
Regarding in particular an engine key of a vehicle. even if the engine key is not used, an engine starter can be operated by directly connecting electrical wires. Consequently, a complete key function cannot be achieved by the general combination of a key and a lock.
Thus, in addition to the key insertion portion equipped with mechanical irregularities and a magnetic force generating portion, a key in which a transmitter element is built is proposed. As an example, the transmitter element can start or continue to operate a vehicle engine only if a receiver element provided at the vehicle receives a specific signal. In this way, movement of the vehicle can be prevented due to the direct connections of the electrical wires or the mechanical destruction.
In general, besides an original key, a so-called card key is used as a key for an automobile. The card key is a thin and light plate-shaped spare key which is made of a synthetic resin or the like and is produced so as to be ready for a case in which the original key is lost. However, unless the transmitter element is provided at the card key serving as a spare key, when the original key is lost, the card key cannot start the vehicle engine.